I have blogged before about the unfortunate phenomenon of the Inappropriate Cultural Flashback while watching an old film – for instance, the sudden distracting presence of someone who would later become massively famous for something else, usually on TV. It is a problem of casting and typecasting – the stars of films may carry with them a kind of shimmer from previous, similar roles which bolster their plausibility and presence in the one you're watching; but if a bit-part player starts reminding you of something absurdly inapposite, you have to work hard to seal off the movie from its showbiz milieu. (Commenters on that blog rightly observed that the problem is most acute in Stanley Kubrick movies such as 2001 and Barry Lyndon, in which Leonard Rossiter will suddenly make a discombobulating appearance.)

Watching the Joseph Losey film Accident – centrepiece of the new Joseph Losey season at BFI Southbank in London – I experienced what I can only describe as a refinement to this problem.

In the film, Dirk Bogarde plays an Oxford academic in middle age. A married father-of-two whose elegant wife (Vivien Merchant) is pregnant with their third child, he is diffident, repressed and dissatisfied with his marriage and dull career. He finds himself sexually attracted to a young student but is entirely without the temperament or emotional vocabulary to express his yearning, restless discontent with life. The film is absorbing, though I found myself sketching an arbitrary link. Jacqueline Sassard, who plays the beautiful student Anna, weirdly wears a sort of sailor suit similar to the one worn by Björn Andrésen, the exquisite boy Tadzio in Visconti's Death In Venice.

There is something even more distracting. Stephen's young daughter is played by … Carole Caplin. And, yes, it does appear to be that Carole Caplin, a sweet miniature six-year-old version of the sleek life-coaching therapist who was to embroil Tony and Cherie Blair in a flat-buying controversy, and who this week was spotted with film and theatre producer Bill Kenwright at his box at Wembley for the FA Cup final.

Like Martin Amis, who had a tiny role in Alexander Mackendrick's A High Wind in Jamaica before taking a different path in life, Carole Caplin dipped a toe in the movie world before prudently removing it. But perhaps she would have had a brilliant career in acting: like a combination of Francesca Annis and Sarah Miles. Carole Caplin might well have made a gutsy cop or pathologist on TV, while also starring in revivals of Ibsen or Bernard Shaw at the Theatre Royal Haymarket. But perhaps it is rather that, like anyone in public life, she has spent her career as an actor, just on a different stage.